Epoxide resin compositions and method

ABSTRACT

A method of improving epoxy resin compositions to provide a cured resin having improved glass transition temperature and toughness characteristics is provided. The method includes providing in an epoxy resin composition an effective amount of a substituted fluorene unit in the composition. The fluorene component acts as a chain extension agent and provides for increased glass transition temperature and less cross-link density. As a result, improved toughness occurs. In preferred applications a toughening agent is provided in the resin composition, to further enhance toughness. Preferred resin compositions, cured resins and methods of providing improved cured resins are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation in-part of U.S. ApplicationSer. No. 137,453 filed Dec. 23, 1987.

FIELD OF THE INVENTION

The present invention relates to epoxy resin compositions, and inparticular to epoxy resin compositions which when cured exhibitpreferred physical and chemical characteristics. Specifically, epoxyresin compositions according to the invention cure to exhibit relativelyhigh glass transition temperatures and high ductility or toughnesscharacteristics.

BACKGROUND OF THE INVENTION

Epoxy resins are monomers or pre-polymers that react with curing agents,through the epoxy functional ring, to yield high performance curedresins. Such resins, for example, are widely utilized as: protectivecoatings for electrical insulation; composite matrix resins; and, asstructural adhesives, due to their combination of desired chemical andphysical characteristics, such as thermal and chemical resistance,adhesion retention and abrasion resistance.

Epoxy resins generally include a plurality of epoxy or oxirane groups.The epoxy groups can react to form a network, typically either throughhomopolymerization or through addition polymerization with an epoxycuring agent. As used herein, the term "epoxy- curing agent" is meant torefer to an agent (or mixture of agents) having three or more reactivesites available for reaction with oxirane groups. As a result of such astructure, an epoxy curing agent can generate a network; i.e. asignificantly cross-linked system.

Epoxy curing agents are to be distinguished from compounds referred toherein as merely chain extension agents. As used herein, the term "chainextension agent" is meant to refer to a compound which has only 2 sitescapable of reaction with oxirane groups. During polymerization, a chainextension agent will typically become lodged between epoxy resin chains,extending same. Little cross-linking occurs, however, since the chainextension agent does not include a third reactive site. As used herein,the term "catalyst" is meant to refer to a compound capable ofcatalyzing polymerization of a di-epoxy resin-compound with substantialnetworking or cross-linking. Generally, this occurs through generationof anionic or cationic polymerization reactions, typically involving theoxirane moiety. During polymerization in the presence of a catalyst, adi-epoxy compound is capable of reacting at four sites, and thussubstantial cross-linking can result.

An example of an epoxy curing agent is a diprimary amine, which iscapable of reacting with four epoxy groups. Typical chain extensionagents include diphenols, such as resorcinol or bisphenol A. Catalystsinclude Lewis acids, tertiary amines and imidazoles.

Throughout this specification, "catalysts" and "epoxy curing agents"will be referred to collectively as "epoxy curatives" or "curatives".

Frequently, it is desired that the cured product have a relatively highglass transition temperature (Tg). The glass transition temperature isthe temperature at which the cured resin changes from a relativelystrong, high modulus, hard, vitreous state to a low modulus, pliable,elastic state. In general, if it is intended that the cured resin bestrong at relatively high temperatures, then a relatively high glasstransition temperature will be necessary.

A commonly used method of obtaining an improved or higher glasstransition temperature is through preparation of a cured resin having ahigh concentration or degree of cross-linking, or a relatively highconcentration of polar groups. A method of achieving high cross-linkingis to use an epoxy curing agent having a high level of functionality, oran active homopolymerization agent. In U.S. Pat. No. 4,331,582,incorporated herein by reference, it is taught thatbis[4-(N,N-diglycidylamino)phenyl]methane (TGDDM) may be cured withdi(4-aminophenyl)sulfone (DDS), to yield a cured resin having a highcross-link density.

Resins having a high cross-link density have several shortcomings. Forexample, such materials are typically very brittle, and thus areundesirable for many applications. That is, the materials are not verytough or ductile. Also, especially if a high concentration of polargroups is utilized to help obtain high glass temperature, the curedpolymer may not be satisfactorily stable to moisture.

Generally, to obtain a relatively tough cured resin, it is desired toutilize a composition which exhibits a high degree of cure, and forwhich, following curing for a reasonably short period of time, a veryhigh percentage of epoxy resin will have reacted to form extended chainswithin the polymer network. Generally, a high concentration of chainextension agent, such as diphenol, can be utilized to accomplish a highdegree of cure. Examples are indicated in U.S. Pat. Nos. 2,934,521 and3,056,762, the disclosures of which are incorporated herein byreference. A problem with such conventional uses of chain extensionagents with conventional epoxy resins is that while the resulting resinsexhibit a relatively high degree of curing and toughness or ductility,generally the glass transition temperature for the cured product isrelatively low, because of low cross-link density.

A substituted fluorene, in particular9,9-bis(4,4,-hydroxyphenyl)fluorene, is known to react with conventionalepoxy polymers, see for example Holloway, Jeffrey G., Low FlammabilityEpoxy Polymers Via, 9,9-Bis(4,4'-Aminophenyl)Fluorene, p. 14, Master'sThesis, San Jose State U. (1984), incorporated herein by reference. Aclass of compounds which include the above-named substituted fluorene isused, as described below, in certain preferred embodiments of thepresent invention, to yield advantages in certain resin compositions. Inparticular, and as will become apparent from the below descriptions,provision in a resin composition polymer units of a formulacorresponding to the residues of 9,9-bis-(4,4,-hydroxyphenyl) fluorenes,leads to advantage.

What has been needed has been a readily curable epoxy resin compositionfor providing a cured resin having both high glass transitiontemperature and improved toughness or ductility; i.e. achievement ofhigh glass transition temperature without high cross-link density orpolarity which may cause brittleness and/or instability to water.Preferably, the desired features are attainable in a resin compositionreadily cured by a readily available and effective agent. Also, methodshave been needed whereby: improved or higher glass transitiontemperature for a cured resin composite can be generated withoutsubstantial loss of toughness; and/or, improved or higher toughness canbe obtained without substantial lowering of glass transitiontemperature.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a resin compositioncapable of being cured to form a cured resin having a relatively highglass transition temperature with relatively high toughness.

It is another object of the present invention to provide a method bywhich an epoxy resin can be cured to a cured state having a relativelyhigh glass transition temperature and a relatively high toughness.

It is another object to the present invention to provide a method bywhich an epoxy resin composition can be improved to cure to a curedstate having improved (higher) glass transition temperature withoutsubstantial loss of toughness, and preferably with improved toughness.

It is another object of the present invention to provide a method bywhich an epoxy resin composition can be improved to cure to a curedstate having improved toughness without any substantial lowering ofglass transition temperature, and preferably with higher glasstransition temperature.

It is yet another object of the present invention to provide a method ofimproving the characteristics of a cured resin, with respect totoughness and glass transition temperature, by providing in that curedresin polymer units or residues comprising selected substituted fluorenemoieties; and in a preferred embodiment providing such moieties in thepresence of a toughening agent.

It is yet another object of the present invention to provide anembodiment comprising a preferred cured resin exhibiting relatively hightoughness and relatively high glass transition temperature, formedthrough the utilization of a bis(hydroxyphenyl) substituted fluorenecompound as a chain extension agent, preferably in conjunction with anepoxy curative such as a curing agent or catalyst.

It is yet another object of the present invention to provide analternate embodiment for a preferred cured resin exhibiting relativelyhigh toughness and relatively high glass transition temperature, throughutilization of a fluorene di-epoxide, preferably in conjunction with anepoxy curative, such as a curing agent or catalyst.

Another object of the invention is to provide a preferred curable epoxyresin composition for use as a film adhesive.

Other objects and advantages of the present invention will becomeapparent from the following descriptions wherein are set forth by way ofillustration and example detailed embodiments of the present invention.

SUMMARY OF THE INVENTION

The present invention concerns the provision of epoxy resin compositionsadvantageously including fluorene units therein. According to twopreferred embodiments of the invention, the fluorene units are providedby means of a substituted fluorene diol component, a substitutedfluorene di-epoxide component, or mixtures of the two. The resultingcompositions are improved, in general, with respect to glass transitiontemperature and ductility. Further, in preferred embodiments a toughenercomposition is provided for further improvement in the characteristicsof the resulting cured material.

A First Embodiment

According to one embodiment of the invention, fluorene-containingbisphenols are provided in a resin composition with a polyepoxide toform, upon curing, a cured resin exhibiting either: improved glasstransition temperature; improved toughness; or both. Generally this isaccomplished through use of fluorene-containing bisphenol(s) in thepresence of a conventional epoxy curative. The terms "high glasstransition temperature" or "improved glass transition temperature" asused herein are generally intended to refer to cured compositions whoseTg has been increased through application of the present invention. Theterms "high" or "improved" toughness are meant to refer to curedcompositions exhibiting increased shear strength and/or peel strength,relative to unimproved compositions. That is, typically conventionalmethods of improving glass transition temperature involve loss oftoughness. When, according to the present invention, an epoxy resincomposition is provided with an improved glass transition temperature,through inclusion of a chain extension agent therein, withoutsubstantial loss of toughness, i.e. no greater than about 20% loweringin shear strength, at ambient temperature and pressure, the resincomposition will be understood to be "improved" In the alternative, whenan epoxy resin is provided with an improvement in toughness, throughinclusion of a chain extension agent therein, without substantiallowering of Tg (<typically about a 25° C. drop), the resin compositionwill also be understood to have been "improved".

In preferred applications of the present invention a toughening agent isused in combination with a chain extension agent to achieve a uniqueimprovement in toughness, along with an improvement in glass transitiontemperature. This will be further understood from examples describedherein.

For preferred compositions according to the present invention, the glasstransition temperature is at least 120° C., and the fracture energy atleast about 100 Joules/m². An improvement in Tg of at least 25° C.without any substantial (typically greater than about 20%) loss intoughness as evidenced by peel strength and/or fracture energy generallydefines a noticeably improved composition according to the invention. Inthe alternative, an improvement of at least about 20 Joules/m² infracture energy at ambient temperature and pressure, without anysubstantial loss (typically greater than about 25° C.) in Tg alsogenerally defines a noticeably improved composition according to theinvention. It will be understood that the amount of Tg and fractureenergy change which indicated a "substantial" change will, in part,depend upon the absolute values of the Tg or fracture energy in theunimproved composition. The above stated figures are intended to berepresentational for what are expected to be commonly used systems.

A variety of epoxy resins may be utilized in improved resin compositionsaccording to the present invention, including both aromatic andaliphatic epoxy resins. Also, a variety of fluorene-containing bisphenolcompositions (including mixtures) may be utilized, generally includingcompounds according to the following formula: ##STR1## wherein: each R²and R¹ is independently selected from hydrogen and other groupssubstantially inert to the polymerization of epoxide group-containingcompounds; for example R⁰ is preferably selected from the groupcomprising: H (hydrogen); the halogens (F, Cl, Br and I); linear andbranched alkyl groups having 1-6 carbon atoms; phenyl groups; nitrogroups; acetyl groups; and trimethylsilyl groups; and, each R¹ ispreferably independently selected from the group comprising: hydrogen(H); phenyl; the halogens; and, linear and branched alkyl groups having1-6 carbon atoms. When it is said that R⁰ and R¹ are "independently"selected, it is meant that there is no requirement that all R⁰ be thesame, or that all R¹ be the same. The terms "fluorene-containingbisphenol composition", "9,9-bis(hydroxyphenyl)fluorene composition" andvariants thereof are meant to refer to single compounds and mixtures ofcompounds according to the above general formula I.

It is noted that the diamino-analogue to the above described compound isalso a chain-extension agent. This compound and its use to improve epoxyresins is the subject of U.S. Pat. No. 4,684,678. That patent is ownedby the assignee of the present invention, Minnesota Mining andManufacturing Co., St. Paul, Minnesota. In general, the di-hydroxycompound is preferred, in part because it is less reactive with epoxycompounds than is the diamine. That is, the resin composition is morereadily stored, handled, and applied, prior to cure, when the di-hydroxyagent is used. Also, the di-hydroxy compound generally dissolves betterin the resin composition mixture. Further, if the resulting fluoreneresidue in the resin is a "di-oxy" rather than a "di-amino" residue, theresin will tend to be more stable.

There is no universal agreement on the terminology to be utilized in thefield of epoxy resins. The term "epoxy resin" has been used to indicateboth: any molecule containing at least one group having a 3-memberoxirane ring; and, also, both uncured and cured compositions. That is,the cured resin is often referred to as an "epoxy resin" even though theepoxy groups may have been reacted and destroyed during the curingprocess.

Herein, the term "polyepoxide resin" refers to a molecule that contains,or contained prior to reaction, more than one oxirane ring. Generally,herein the term "epoxy resin composition" refers to the uncuredcomposition which, upon curing, cures to a "cured epoxy resin" The term"epoxy resin composition"may be used to refer to resin prior tocross-link; and, to non-reacted or partially reacted material, prior tofinal reaction and cross-link. When it is said herein that an epoxyresin composition "includes" or "comprises" it is meant that thecomposition either: comprises a mixture that includes the namedcomponents unreacted; or, includes resulting polymer or polymer materialformed from polymer-forming reaction(s) of those components, to leaveresidue(s) therefrom in the polymer; or, the composition includes both.

Preferred epoxy resin compositions according to the present inventioninclude an effective amount of a toughening agent therein. A variety oftoughening agents are well-known. They generally comprise elastomermolecules and similar compounds which are incorporated into the resincomposition but which do not necessarily become chemically involved inthe curing process. That is, the compounds may sometimes remainindependent in the matrix defined by the cured resin. The presence ofthe compounds imparts preferred physical characteristics to the curedresin, relating generally to decreased brittleness and increasedtoughness. In some instances, the toughening agent may be chemicallyincorporated into the epoxy resin itself, for example as a substituenton the epoxy-containing component. An "effective" amount of a tougheningagent is an amount effective to impart an improvement in toughness tothe cured resin composition. This may be characterized as an improvementof at least about 20% in the peel strength, at ambient temperature andpressure. The term "toughening agent" and variants thereof, as usedherein, will be understood to include mixtures containing a plurality ofsuch agents.

According to the first embodiment of the present invention, a method ofimproving an epoxy resin composition, whereby a resulting cured epoxyresin is provided with improved glass transition temperature andimproved toughness, comprises provision of a chain extension agentcomprising a 9,9-bis(hydroxyphenyl) fluorene component in an effectiveamount in the epoxy resin composition. An "effective amount" of the9,9-bis(hydroxyphenyl)fluorene is an amount sufficient to impartimprovement in Tg and/or toughness of the cured resin composition, asabove defined. Preferably, as above indicated, a toughening agent isalso provided.

As previously indicated, in certain applications of the presentinvention an epoxy resin composition is provided with both: a9,9-bis(hydroxyphenyl)fluorene component; and, an epoxy curativecomponent. In this manner, the difunctional fluorene component may beused to increase epoxy resin chain length, without introduction ofincreased cross-linking. The curative, on the other hand, is used tointroduce sufficient cross-linking to result in strength and integrityof cured resin. Typically, the amount of 9,9-bis(hydroxyphenyl)fluoreneutilized is such that about 5-90% and preferably about 9-70%, ofreactive oxirane rings in the epoxy resin will react with activehydroxy-groups provided by the substituted fluorene component.Preferably less than 50% of the oxirane units are reacted with thesubstituted fluorene, for many applications. Generally, both thesubstituted fluorene and the epoxy resin are di-functional with respectto this reaction, thus the ratio of reactive epoxy resin molecules toreactive fluorene compound should be between about 1:0.05 and 1:0.9, andtypically about 1:0.09-1:0.7. By "di-functional" it is meant that eachepoxy resin molecule includes only two reactive oxirane moieties, andeach 9,9-bis(hydroxyphenyl)fluorene molecule includes only two reactivehydroxy groups.

The amount of curative used will depend on its degree of reactivity andin some instances its relative reactivity with respect to the fluorenecomponent. Generally, it should be selected and used in an amountsufficient or effective for reaction with a substantial amount ofremaining reactive oxirane moieties in the epoxy resin, i.e. those epoxyor oxirane moieties in excess of the reactive hydroxy-moieties on thefluorene component. The term "a substantial amount" as used herein, inthis context, is meant an amount sufficient to generate enoughcross-linking to result in a cured polymer having the desired Tg andtoughness. As an example, if a curative capable of reacting with 3oxirane units were selected, it could be used in a molecular ratio ofabout 2:3 with the excess epoxy resin; i.e. that amount of epoxy resinin excess over the fluorene component. It is noted that mixtures ofcuratives may be used, including mixtures of components having differingreactivities or available reactive sites for cross-linking. The term"curative" as used herein is meant to include mixtures of curatives.

The result of the above is generally improved cured resins. Also, theresin composition is made particularly susceptible to enhancements bytoughening agents. A reason for this may be that the lengths ofepoxy-chain units, or polymer backbone, between cross-links is generallyincreased, by comparison to non-improved resins, due to the presence ofthe bis(phenyl-substituted) fluorene residue. A result is that thepolymer can arguably distort around the toughener, leading to better orenhanced incorporation of the toughener with resulting beneficialeffects therefrom.

In a typical process according to the present invention, the epoxy resincomposition is prepared and is heated to the appropriate curingtemperature, for a length of time sufficient to substantially completelycure the composition. Generally, preparation of the composition involvesa pre-dispersing of any toughening agent in the epoxide compound,followed by mixing of the resulting toughener/epoxide mix with the chainextension agent (i.e. the 9,9-bis(hydroxyphenyl)fluorene composition)and curative. Preferred compositions according to the present inventioncan be cured between the temperatures of about 50° C. and about 300° C.In conventional manners curing temperature cycles may be applied, tofacilitate curing in a desired manner and at a selected rate. Typically,it is desired to have complete curing within a time period of about 10minutes to 12 hours (overnight).

The cured resin may be effectively used as a bonding film or filmadhesive in a variety of applications. Typically, they will be used asadhesive films between first and second substrates, to form afilm/substrate arrangement. For example, the adhesive might be used toattach aluminum skins to an airplane framework. In general, the resincompositions can be readily applied as films, and then cured. Preferablythe bonding film is made about 0.0005-0.030 inches (0.001-0.070 cm)thick.

For typical applications, a composite is formed comprising a film(preferably 0.001-0.070 cm thick) of the uncured or partially curedresin on a substrate such as a conventional release liner. The releaseliner may be utilized to apply the adhesive film to location or situs atwhich an adhesive bond is to be formed. The release liner is thenstripped away, exposing the adhesive film in position on the firstsubstrate. A second substrate to be adhered to the first substrate isthen brought into contact with the adhesive film, and the composite isheated to complete cure. Typical materials useable as the release linerinclude: silicone treated flexible substrates such as treated paper orplastic.

A typical polyepoxide usable in compositions according to the presentinvention is 2,2-bis-[4-(2,3-epoxypropoxy)phenyl]propane, compound IIbelow: ##STR2##

Upon curing in the presence of a fluorene composition according to thepresent invention, an epoxide resin including such units as III belowwill result. ##STR3##

By formula III, it is not meant to suggest that the cured resincomprises only alternating epoxy unit residue and fluorene unit residue,but rather that both are included in the cured resin, generally in thealternating manner. As indicated previously, a substantial amount of theepoxy resin oxirane units will have reacted to form cross-linking, as aresult of the curative. The amount of oxirane units linked tosubstituted fluorene may be varied considerably. However generally, fortypical applications about 5-90%, and preferably about 9-50%, of theoxirane units will have been linked to a substituted fluorene compoundas indicated at III above.

It will be apparent from a review of formula III above, that many of theadvantages of the present invention are derived from the fact polymerunits or residues according to the general formula IV below, areprovided in a epoxide resin, in a preferred and effective amount. Unitsaccording to IV below will be sometimes generally referred to herein asoxy-terminated substituted fluorene units or residues. Preferred epoxideresins (according to formula IV below wherein R⁰ and R¹ are both H) ofthe present invention include about 2 to 78 weight percent, and morepreferably about 4 to 60 weight percent, of such moieties or units, forachievement of preferred characteristics as described. Formula IV is asfollows: ##STR4## wherein: each R¹ and R¹ is independently selected fromhydrogen and other groups substantially inert to the polymerization ofepoxide group-containing compounds; for example R⁰ is preferablyindependently selected from the group comprising: H (hydrogen); thehalogens (F, Cl, Br and I); linear and branched alkyl groups having 1-6carbon atoms; phenyl groups; nitro groups; acetyl groups; and,trimethylsilyl groups; each R¹ is preferably independently selected fromthe group comprising: hydrogen (H); phenyl; the halogens; and linear andbranched alkyl groups having 1-6 carbon atoms. When it is said that R⁰and R¹ are "independently" selected, it is meant that there is norequirement that all R⁰ be the same, or that all R¹ be the same. When R¹and R⁰ are not all H, the weight percent of the units will possibly behigher, preferably within the range of about 2 to about 90%.

An Alternate Embodiment

An alternate method of providing resin or polymer units according to IVabove in resin compositions or epoxide resins possessing theadvantageous characteristics described herein, comprises reaction,during resin formation, of material or extension agent according togeneral formula V as follows: ##STR5## wherein: each R⁰ and R¹ isindependently selected from hydrogen and other groups substantially andinert to the polymerization of epoxide group-containing compound; forexample R⁰ is preferably independently selected from the groupcomprising: H (hydrogen); the halogens (F, Cl, Br and I); linear andbranched alkyl groups having 1-6 carbon atoms; phenyl groups; nitrogroups; acetyl groups; and, trimethylsilyl groups; and, each R¹ ispreferably independently selected from the group comprising: hydrogen(H); phenyl; the halogens; and linear and branched alkyl groups having1-6 carbon atoms; and, each R² is an epoxy-functionalized alkyl groupcapable of reacting through the epoxy group to form epoxy resins,preferably wherein each R² is, independently, a terminalepoxy-functionalized alkyl group having 1-6 carbon atoms. Mostpreferably each R² is a 2,3-epoxypropyl qroup. When it is said that R⁰,R¹ and R² are "independently" selected it is meant that there is norequirement that all R⁰ be the same, or that all R¹ be the same, or thatall R² be the same. It will be understood that a mixture of materialsmay be utilized as this component, which is generally referred to hereinas the "fluorene di-epoxy" or "fluorene di-epoxide" component.Preferably the resin composition, or bonding film formed therefrom,includes about 5 to 97% by weight of the di-epoxide V.

Thus, while in the first embodiment the fluorene units IV wereincorporated into the resin through reaction of a bisphenol chainextension agent according to general formula I, for the alternateembodiment the units IV are incorporated into the resin through reactionof a di-epoxide compound, which can copolymerize with other epoxycompounds and/or polymerize with other chain extenders such as diolchain extenders. A preferred such fluorene di-epoxide compound is thediglycidyl ether, epoxide of 9,9-bis (4-hydroxyphenyl) fluorene, VI,(for example available under the Tradename EPON RSS 1079, from ShellChemical Co.).

Formula VI is as follows: ##STR6## wherein: R⁰ and R¹ are H.

In general, similar principles, procedures, features and advantages areof concern when the fluorene di-epoxide compounds V are used, as thosewhich were of concern and were described above for the fluorenebis-hydroxy chain extension materials. For example a variety of epoxyresins may be utilized to copolymerize with the material, including botharomatic and aliphatic epoxy resins. Also, preferred compositionsinclude an effective amount of a toughening agent therein, for thedevelopment of preferred physical characteristics in the cured resin,generally relating to improved Tg and/or toughness.

Preferably, the amount of fluorene di-epoxide V (when R⁰ and R¹ are Hand R² is 2,3-epoxypropyl) utilized is such that about 2 to 78%, byweight, of the resulting resin comprises the fluorene residue units IV.In general, this is readily achieved by providing a ratio of moleculesof reactive non-fluorene copolymers and reactive non-fluorene chainextenders to diepoxy fluorene of between about 1:0.05 and 1:0.9 andpreferably between about 1:0.09 and 1:0.7. In preferred compositions asubstantial amount of diol chain extender is used. Preferably the ratioof reactive epoxy molecules (including diepoxide fluorene materials), todiol chain extenders should also be between about 1:0.05 and 1:0.9, andpreferably at 1:0.09 to 1:0.7.

DETAILED DESCRIPTION OF THE PREFERRED AND ALTERNATE EMBODIMENTS

As required, detailed embodiments of the present invention are describedin detail herein. It is to be understood, however, that the detailsprovided are only exemplary of the invention, which may be embodied invarious forms. Therefore, the specific details disclosed herein are notto be interpreted as limiting, but rather as a basis for the claims andas a representative basis for teaching one skilled in the art tovariously employ the present invention in virtually any appropriatesystem, arrangement or manner.

FIRST EMBODIMENT - BIS(HYDROXPHENYL) FLUORENE CHAIN EXTENSION AGENT

Preferred improved epoxy resin compositions according to a firstembodiment of the present invention include: polyepoxides or residuetherefrom; a chain extension agent composition, or residue therefrom(i.e. the fluorene-containing bisphenol component); tougheners; and,curative, or residue therefrom (curing agent and/or catalyst), asfollows:

The Epoxide Constituent

For preferred compositions according to the present invention, theepoxide constituent comprises any of a variety of polyepoxides, and mayinclude mixtures. It will be understood that the scope of the terms usedherein in discussion of this component, and other components, in theresin composition are meant to include residues from reaction or partialreaction with other components to form polymeric (or oligomeric)structures. Polyepoxides are well known. Preferred aromatic polyepoxidesfor use according to the present invention include: the polyglycidylethers of polyhydric phenols; glycidyl esters of aromatic carboxylicacids; N-glycidylaminobenzenes; and, glycidylamino-glycidyloxybenzenes.

Examples of N-glycidylaminobenzenes suitable for use in the epoxy resincompositions of the present invention include the di-and polyglycidylderivatives of: benzeneamine; benzene diamines; naphthylenamine; and,naphthylene diamines. Such compounds include:N,N-diglycidylbenzeneamine; N,N-diglycidylnaphthalenamine;1,4-bis(N-glycidylamino)benzene; and, 1,3-bis(N,N-glycidylamino)benzene.The polyglycidyl derivatives of aromatic aminophenols are described inU.S. Pat. No. 2,951,825, incorporated herein by reference. An example ofthese compounds is N,N-diglycidyl-4-glycidyloxy-benzeneamine.

Aliphatic polyepoxides may also be used, and are well known. Mostpreferably, the aromatic polyepoxides used in resin compositionsaccording to the invention are the polyglycidyl ethers of polyhydricphenols. The preferred aliphatic epoxides are the diglycidylethers ofcyclohexane dimethanol.

The polyepoxides are exemplified by the following: vinyl cyclohexenedioxide; epoxidized mono-, di- and triglycerides; butadiene dioxide;1,4-bis(2,3-epoxypropoxy)benzene; 1,3-bis(2,3-epoxypropoxy)benzene;4,4,-bis(2,3-epoxypropoxy)diphenyl ether;1,8-bis(2,3-epoxypropoxy)octane; 1,4-bis(2,3-epoxypropoxy)cyclohexane;4,4,-bis(2-hydroxy-3,4-epoxybutoxy)diphenyl dimethyl methane;1,3-bis(4,5-epoxypentoxy)-5-chlorobenzene;1,4-bis(3,4-epoxybutoxy)-2-chlorocyclohexane; diglycidyl thioether;diglycidyl ether; 1,2,5,6-diepoxy-hexyne-3; and, 1,2,5,6-diepoxyhexane.Other usable epoxides are found in Handbook of Expoy Resins, Lee andNeville, McGraw-Hill, New York (1967), and U.S. Pat. No. 3,018,262,incorporated herein by reference. Some compounds include epoxides listedin U.S. Pat. No. 3,298,998, incorporated herein by reference. Thesecompounds include:

bis[p-(2,3-epoxypropoxy)phenyl]cyclohexane;

2,2-bis[p-(2,3-epoxypropoxy)phenyl]norcamphane;

5,5-bis[(2,3-epoxypropoxy)phenyl]hexahydro-4,7-methanoindane;

2,2-bis[4-(2,3-epoxypropoxy)-3-methylphenyl]hexahydro-4,7methanoindane;and,

2-bis[p-2,3-epoxypropoxy)phenyl]-methylene-3methylnorcamphane.

The Chain Extension Agent

The chain extension agent usable according to the first embodiment ofthe present invention is a 9,9-bis(hydroxyphenyl)fluorene compositionand preferably includes at least one compound of the general formulaVII, as follows: ##STR7## wherein: each R⁰ and R¹ is independentlyselected from substituents non-reactive with epoxy groups in the resin;for example: each R⁰ is preferably independently selected from the groupcomprising hydrogen (H); the halogens (F, Cl, Br and I); linear orbranched alkyl groups having 1-6 carbon atoms; phenyl-; nitro-; acetyl-;and trimethylsilyl-; and, each R¹ is independently selected from thegroup comprising: hydrogen (H); phenyl-; the halogens; and, alkyl groupshaving 1-6 carbon atoms. The 9,9-bis(hydroxyphenyl)fluorene compositionmay include more than one compound according to formula VII.

When it is herein said that R⁰ and R¹ are "independently" selected, itis meant that there is no requirement that all groups R⁰ be the samegroup, or that all groups R⁰ be the same group.

Examples of chain extension agents (bisphenol fluorenes) according toformula IV include:

9,9-bis(4-hydroxyphenyl)fluorene,

9,9-bis(3-methyl-4-hydroxyphenyl)fluorene,

9,9-bis(3-chloro-4-hydroxyphenyl)fluorene,

9,9-bis(3-ethyl-4-hydroxyphenyl)fluorene,

9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene,

9,9-bis(3,5-dichloro-4-hydroxyphenyl)fluorene,

2-iodo-9,9-bis(4-hydroxyphenyl)fluorene,

3-bromo-9,9-bis(4-hydroxyphenyl)fluorene,

1-chloro-9,9-bis(4-hydroxyphenyl)fluorene,

2-methyl-9,9-bis(4-hydroxyphenyl)fluorene,

2,6-dimethyl-9,9-bis(4-hydroxyphenyl)fluorene,

1,5-dimethyl-9,9-bis(4-hydroxyphenyl)fluorene,

2-fluoro-9,9-bis(4-hydroxyphenyl)fluorene,

1,2,3,4,5,6,7,8-octafluoro-9,9-bis(4-hydroxyphenyl)fluorene,

2,7-dinitro-9,9-bis(4-hydroxyphenyl)fluorene,

2-chloro-4-methyl-9,9-bis(4-hydroxyphenyl)fluorene,

2,7-dichloro-9,9-bis(4-hydroxyphenyl)fluorene,

2-acetyl-9,9-bis(4-hydroxyphenyl)fluorene,

2-chloro-9,9-bis(4-hydroxyphenyl)fluorene, and

2-t-butyl-9,9-bis(4-hydroxyphenyl)fluorene.

Mixtures of hydroxyphenyl fluorenes may be utilized as the chainextension agent, in compositions according to the present invention.Mixtures may be preferred in some instances because they often have amelting point that is lower than the melting point of an individualhydroxyphenyl fluorene, and thus facilitate curing of the epoxy resincomposition at a temperature lower than might otherwise be possible.

The amount of chain extension agent used in resin compositions accordingto the present invention may be varied somewhat. Preferably, the amountof chain extension agent used is based on the amount of reactive epoxidefunctionality in the polyepoxy resin, generally according to theformula: 1 reactive hydroxy equivalent or less ofbis(hydroxyphenyl)fluorene per equivalent of epoxide group present inthe polyepoxide component. A wide range is possible in applications ofthe present invention. A range of about 0.05 to about 0.9 is preferable,as it permits a significant amount of epoxide group to react incross-linking. A most preferred range of ratios of fluorene hydroxyequivalent to reactive epoxy or oxirane equivalent is about 0.09-0.5.The term "hydroxy equivalent" when used with respect to thefluorene-containing bisphenol is meant to refer to equivalents ofreactive hydroxy groups, i.e. the 9-hydroxy groups. Reference toequivalents of epoxy group in the polyepoxide is meant to refer toreactive epoxy groups.

Curing Agents and Catalysts (Curatives)

The epoxy curatives, curing agents and/or catalysts suitable for use incompositions according to the present invention include thoseconventionally used for curing epoxy resin compositions and formingcross-linked polymer networks. Such agents include aliphatic andaromatic primary amines, for example: di(4-aminophenyl)sulfone;di-(4-aminophenyl)ethers; and 2,2-bis(4aminophenyl)propane. Suchcompounds also include aliphatic and aromatic tertiary amines such asdimethylaminopropylamine and pyridine, which may act as catalysts togenerate substantial cross-linking. Further, boron trifluoride complexessuch as BF₃ -monoethanolamine; imidazoles such as2-ethyl-4-methylimidazole; hydrazides such as aminodihydrazide;guanidines such as tetramethyl guanidine; and, dicyandiamide are usefulas curing agents or catalysts.

The amount of curing agent and/or catalyst needed will vary from resinto resin and is generally to be provided in such an amount as to beeffective in causing substantially complete curing within a desiredlength of time. A typical composition according to the present inventionincludes about 1-30%, by weight, of curing agent. It will be understoodthat the final properties of the cured resin composition will be greatlyinfluenced by the relative amounts of cross-linking and epoxy chainextension caused respectively by the curative and chain extension agent.Generally, this is set by selecting the amount of equivalents ofsubstituted fluorene(s) as the chain extension agent, and then using anappropriate amount of curative to achieve curing at a selected rate.

The Toughening Agent

Toughening agents for use in preferred compositions of the presentinvention generally comprise: elastomer molecules, separate elastomerprecursor molecules; combination molecules that include epoxy-resinsegments and elastomeric segments; and, mixtures of such separate andcombination molecules. The combination molecules may be prepared byreacting epoxy resin materials with elastomeric segments; the reactionleaving reactive functional groups, such as unreacted epoxy groups, onthe reaction product. The general use of tougheners in epoxy resins iswell-known, and is described in the Advances in Chemistry Series No. 208entitled "Rubbery-Modified Thermoset Resins", edited by C. K. Riew andJ. K. Gillum, American Chemical Society, Washington, 1984, the referencebeing incorporated herein by reference. The amount of toughening agentto be used depends in part upon the final physical characteristics ofthe cured resin desired, and is generally determined empirically. For atypical preferred embodiment, the toughening agent comprises 2-40% andpreferably about 4-20% by weight of the resin composition.

Some useful toughening agents include: carboxylatedacrylonitrile/butadiene vulcanizable elastomer precursors (such asHycar® CTBNX and Hycar® 1072, B. F. Goodrich Chemical Co.); butadienepolymer (Hycar® CTB, B. F. Goodrich Chemical Co.); amine functionalpolyethers such as: HC1101 (a 10,000 MW, primary amine-terminated,compound; Minnesota Mining and Manufacturing Co.; St. Paul, c, Minn.),Jeffamine® (Texaco Chemical Co.); and isocyanate-functional polyetherssuch as: Adiprene® (Uniroyal Chemical Co.); functional acrylic rubbersincluding acrylic core/shell material, such as Acryloid® KM330 and 334,Rohm & Haas; and core/shell polymers, such asmethacrylate-butadiene-styrene (MBS) copolymer wherein core iscrosslinked styrene/butadiene rubber and shell is polymethylacrylate(Acryloid® KM653, Acryloid® KM680; Rohm and Haas).

As used above, for acrylic core/shell materials "core" will beunderstood to be acrylic polymer having Tg<0° C. and "shell" will beunderstood to be an acrylic polymer having Tg>25° C. Tougheners mayinclude epoxy-terminated compounds, which can be incorporated into thepolymer backbone.

A typical, preferred, list of tougheners comprises: acrylic core/shellpolymers; styrene-butadiene/methacrylate core/shell polymers; polyetherpolymers; carboxylated acrylonitrile/butadienes; and, carboxylatedbutadienes.

Advantages can be obtained from the provision of the chain extensionagent in a composition with an epoxy resin even in the absence of atoughening agent as described above. However, particular advantage isachieved from the presence of the toughening agent, as indicated byExample 2, and as previously suggested. It is a feature of the presentinvention that improved resins as disclosed herein are generally madeparticularly susceptible to, or are enhanced with respect to, thebeneficial effects of tougheners.

Adjuvants

Various adjuvants may be added to compositions according to the presentinvention, to alter the characteristics of the cured composition.Included among useful adjuvants are: thixotropic agents such as fumedsilica; pigments such as ferric oxide, brick dust, carbon black, andtitanium oxide; fillers such as silica, magnesium sulfate, calciumsulfate, and beryllium aluminum silicate; and, clays such as bentonite.Amounts of up to about 200 parts of adjuvant per 100 parts of epoxyresin composition may be effectively utilized.

Formation and Use of the Epoxy Resin Compositions

Generally, the toughening agent is pre-dispersed in the epoxidecompound. The toughener-containing epoxide is then mixed with a curativeand the chain extension agent to form a substantially uniform mixture.The mixture is cured upon heating for an appropriate length of time.While the curing reaction may take place slowly at room temperature, itis preferably brought about by heating the mixture to about 50° C. to150°-300° C. for an appropriate length of time. Often heating cycles maybe utilized, such as, for example, 50° C. for 0.25-1.0 hours, 150°-200°C. for 0.5-2.0 hour and 175°-250° C. for 1.0-5.0 hours.

In some instances it may be preferred to react all of the chainextension agent with the resin, before curing is initiated. This will,in part, depend on the percent of chain extension agent to beincorporated.

It is observed that compositions according to the present invention areparticularly advantageous, by comparison to the compositions of U.S.Pat. No. 4,684,678. Generally, this results from greater stability ofthe dihydroxy compound relative to the diamine.

The resin compositions of the invention are useful, for example: asstructural adhesives; as films or protective coatings for variousarticles such as appliances; as impregnating and embedding materials forelectrical components; and, in other uses, especially those wherein theoperating temperature of the article or material is expected to besubstantially elevated over room temperature.

THE SECOND EMBODIMENT -- FLUORENE DIEPOXIDE EXTENSION AGENT

As described above, in alternate embodiments the oxy-terminatedsubstituted fluorene units IV are introduced into the polymer resinthrough reaction of a diepoxy compound (or extension agent) includingthe fluorene residue therein, rather than through a dihydroxy chainextension agent. Preferred improved epoxy resin compositions accordingto this embodiment of the present invention include: a fluorenedi-epoxide component, or residue therefrom; a non-fluorene chainextension component (for example a non-fluorene di-epoxide or residuetherefrom, and/or a non-fluorene diol, or residue therefrom); an epoxycurative component; toughener; and, curative or residue therefrom(curing agent and/or catalyst), as follows:

The Fluorene Di-epoxy Constituent

As previously described, for compositions according to the alternateembodiment of the present invention, the fluorene di-epoxy constituentcomprises any of a variety of di-epoxides, including mixtures, of thefollowing general formula V: ##STR8## wherein: each R⁰ and R¹ isindependently selected from hydrogen and other groups substantially andinert to the polymerization of epoxide group-containing compound; forexample R⁰ is preferably independently selected from the groupcomprising: H (hydrogen); the halogens (F, Cl, Br and I); linear andbranched alkyl groups having 1-6 carbon atoms; phenyl groups; nitrogroups; acetyl groups; and, trimethylsilyl groups; and, each R¹ ispreferably independently selected from the group comprising: hydrogen(H); phenyl; the halogens; and linear and branched alkyl groups having1-6 carbon atoms; and, each R² is an epoxy-functionalized alkyl groupcapable of reacting through the epoxy group to form epoxy resins,preferably wherein each R² is, independently, a terminalepoxy-functionalized alkyl group having 1-6 carbon atoms. Mostpreferably each R² is a 2,3-epoxypropyl group. When it is said that R⁰,R¹, and R² are "independently" selected it is meant that there is norequirement that all R⁰ be the same, or that all R¹ be the same, or thatall R² be the same. It will be understood that a mixture of materialsmay be utilized as this component, which is generally referred to hereinas the "fluorene di-epoxy" or "fluorene di-epoxide" component.

Preferably, the fluorene diepoxide is a diglycidyl ether epoxide ofbis(hydroxyphenyl) fluorene, and more preferably it is the diglycidylether epoxide of a 9,9-bis(hydroxyphenyl) fluorene. Most preferably, itis 9,9-bis(4,4,-(2,3-epoxypropoxy)phenyl) fluorene: ##STR9## wherein: R⁰and R¹ are H.

Chain Extension Agents

If the substituted fluorene residue IV is incorporated into the resin bymeans of a fluorene diepoxide V, according to the second embodimentdescribed herein, a non-fluorene containing chain extension agent may bedesirable in order to provide for certain preferred characteristics inthe resulting resin or polymer. A variety of materials may be utilizedas the non-fluorene containing chain extension agent, including mixturesof materials. For example, the non-fluorene containing chain extensionagent may include conventional bisphenols such as bisphenol A, bisphenolF, bisphenol S, resorcinol, catechol, hydroquinone and mixtures thereof.Alternatively, the chain extension agent may be another difunctionalactive hydrogen compounds, capable of chain extending, for example adiglycidal ether epoxy resin. These compounds may include dimercaptans,dicarboxylic acids, amines and diamines. It is noted that fluoreneresidue VI could, in part, be provided by a diol chain extension agentas previously described.

Copolymerizing Epoxide Constituent

In some applications, according to the alternate embodiment,compositions according to the invention may include polyepoxides ormixtures of polyepoxides copolymerizable with the fluorene di-epoxide.It will be understood that the scope of the terms used herein, withrespect to this component, as with other components, in the resincomposition is meant to include residues from reaction or partialreaction with other components to form polymeric structures.Polyepoxides are well known. Preferred aromatic polyepoxides for use asthis component, in compositions according to the present invention,include: the polyglycidyl ethers of polyhydric phenols; glycidyl estersof aromatic carboxylic acids; N-glycidylaminobenzenes; and,glycidylaminoglycidyloxybenzenes. In general, the non-fluorenecontaining, copolymerizable epoxide constituent maybe generally asdescribed for the "epoxide constituent" of the previously describedembodiment.

Curing Agents and Catalyst (Curatives)

The epoxy curatives curing agents and/or catalysts suitable for use incompositions according to this embodiment include those materialsconventionally used for curing epoxy resins compositions and formingcross-linked polymer networks. The agents include primary aminesincluding both aliphatic and aromatic primary amine, for example:di(4-aminophenyl)sulfone; di-(4-aminophenyl) ether; and,2,2-bis(4-aminophenyl)propane. Such compounds also include aliphatic andaromatic tertiary amine such as dimethylaminopropylamine and pyridine,which may act as catalyst to generate substantial cross-linking.Further, boron trifluoride complexes such as BF₃ -monoethanolamine;imidazoles such as 2-ethyl-4-methyl-imidazole; hydrazides such asaminodihydrazide; guanidines such as tetramethyl guanidine; and,dicyandiamide are useful as curing agents or catalysts. In general, thecuring agents and catalysts (curatives) may be as previously describedfor the embodiment utilizing bis(hydroxphenyl) fluorene chain extensionagents, and the curatives may be utilized in a same manner and a similaramount by weight.

The Toughening Agent

Toughening agents for use in compositions according to the embodiment ofthe present invention involving the fluorene di-epoxide component as thecomponent for introduction of substituted fluorene residue IV into theresin, may be the same toughening agents as those usable with the firstembodiment described, wherein bis(hydroxyphenyl) fluorene was utilizedto introduce the residue IV. As previously described, in general suchtoughening agents comprise: elastomer molecules, separate elastomerprecursor molecules; combination molecules that include epoxy-resinsegments and elastomeric segments; and, mixtures of such separate andcombination molecules.

Adjuvants

Various adjuvants maybe utilized in compositions according to the secondembodiment. Generally they may be as described above for the firstembodiment.

Formation and Use of the Epoxy Resin Compositions of the SecondEmbodiment

In general , epoxy resin compositions prepared from constituentsaccording to the second embodiment may be formed and used in mannersgenerally analogous to those described above for epoxy resincompositions formed according to the first embodiment. That is,generally the toughening agent is pre-dispersed in the epoxidecompound(s). It is noted, however, that in the case of the secondembodiment the epoxide compound(s) includes the fluorene di-epoxidecompound. The toughener-containing epoxide is then mixed with acurative, and any chain extension agent utilized, to form asubstantially uniform mixture. It is noted that the chain extensionagent, for the second embodiment, will generally comprise anyconventional difunctional chain extension agents, such as the diol chainextension agents described above. Further, the chain extension agent mayinclude some of the bis(hydroxyphenyl) fluorene chain extension agentdescribed above for the first embodiment.

The composition or mixture is cured upon heating for an appropriatelength of time. While the curing reaction may take place slowly at roomtemperature, it is preferably brought about by heating the mixture toabout 50° C. to 150°-300° C. for an appropriate length of time. In someinstances heating cycles may be utilized, such as, for example, 50° C.for 0.25 to 1.0 hours, 150 to 200° C. for 0.5.to 2.0 hours and 175° to250° C. for 1.0 to 5.0 hours.

In some instances, it maybe preferred to react substantially all of thechain extension agents with the resin, before curing is initiated. Thiswill, in part, depend upon the percent of chain extension agent to beincorporated.

In general, compositions prepared according to the alternate embodimentwill exhibit similar properties to those compositions prepared accordingto the first embodiment described, and will be analogously useful. Theymay, for example, be formed into films applied by means of a releaseliner or substrate, to a site for use.

EXAMPLES

The following examples illustrate specific embodiments and applicationsof the present invention. In all examples all parts and percents are byweight, and temperatures are in degrees Centigrade unless otherwisenoted. In the examples, the overlap shear strength and floating rollerpeel strength of cured resins is given. This is generally as determinedand described in ASTM D-3167-7b and MMM-A-132, unless otherwise noted.Results are typically calculated in megapascals (MPa) and/or kilogramsper centimeter (kg/cm). Peel strength and fracture energy relate totoughness and ductility in that the higher the peel strength andfracture energy, the greater the toughness of the material. This isinterpreted herein as improved toughness or ductility.

FORMULATIONS ACCORDING TO THE FIRST EMBODIMENT EXAMPLE 1

The 9,9-bis(4-hydroxyphenyl)fluorene chain extension agent was preparedas follows:

A 500 ml 3-necked flask was equipped with a thermometer and means forintroducing hydrogen chloride. To the flask were added: 90.0 g fluorene;282.0 g phenol; and, 3.1 g 3-mercaptopropionic acid. The mixture washeated to 55° C., with stirring.

Anhydrous hydrogen chloride (9.0 g) was flushed through the reactionflask over about a 30 minute period. The mixture was reacted for about 6hours at 55° C., and was poured into 3 liters of methanol. Theprecipitate was collected and recrystallized from 1,2-dichloroethane toyield 130 g of white crystals, melting pt. 224.5°-225.5° C. Conventionalanalysis indicated that the crystals were9,9-bis(4-hydroxyphenyl)fluorene. This material is referred to herein asmonomer F.

EXAMPLE 2

Polymerization of an epoxy resin with 9,9-bis(4-hydrophenyl)fluorene.

To a resin flask fitted with a mechanical stirrer and a thermometer: 49g of diglycidyl ether of bisphenol A, epoxide (equivalent weight193-203), (Epon® 829, Shell Chemical Co.); and, 12.25 g9,9-bis(4-hydroxyphenyl)fluorene (monomer F), prepared as above, wereadded. The mixture was heated to about 121° C. with continuous stirring,and was maintained at 115°-127° C. until a uniform mixture was obtained,i.e. 15-30 minutes. Polytetramethylene oxide diprimary amine, 12.5 g, Mwabout 2,000 (HC 1101, 3M Co.), which had been melted at about 82° C. wasadded slowly to the reaction flask with stirring. The mixture was heatedat about 177°-204° C. for about 120 minutes, was dumped and cooled atabout 25° C. on silicone treated kraft paper, and was then dissolved inan 85-15 mixture of methyl ethyl ketone and toluene. This mixture isreferred to herein as "Component A".

A "Component B" was prepared by milling together: 8.1 g of diglycidylether of bisphenol A, epoxide equivalent weight about 182-200 (Epon®828, Shell Chemical Co.); 4.5 g dicyandiamide (Aero®, American CyanamidCo.) and 1.8 g of a reaction product of toluenediisocyanate anddimethylamine (TDI Urea), on a 3-roll paint mill to a fineness of NS 4+.NS 4+indicates a particle size ≦0.005 cm. The grinding is done untilwhen film of the material is viewed at grazing incidence 5-10 particleswithin a 3 mm band appear through the surface.

The following were added to a double tite tin: 2.5 g Epon.® 828; 10.0 gcondensation polymer of epichlorohydrin and Bisphenol A, epoxideequivalent weight about 230-280 (Epon.® 834, Shell Chemical Co.); 12.25g 9,9-bis(4-hydroxyphenyl)fluorene; Component A; and, Component B. Adouble tite tin is a can having a friction top which seals against bothan inside and outside lip, for example a typical paint can. The mixturewas blended on a roller mill. For testing purposes a dry film wasprepared by coating the mixture on a silicone treated polyethylenecoated paper backing at a wet thickness of about 0.25 mm, with a dryingof the film for about 60 minutes at about 24° C. followed by treatmentfor about 60 minutes at 66° C. in a fresh air circulating oven. Thismaterial is identified herein as "Film A"

The shear strength was determined according to Federal Specification MMMA-l32A and peel strength was determined according to ASTM D-3167-7busing 2024 T-3 aluminum panels which had been first deqreased byexposing panel to hot (about 138° C.) vapors of perchloroethylene forabout 15-20 minutes, drying in air, immersing in alkaline degreaser("Oakite Aluminum Cleaner 164", Oakite Products Inc., Berkeley Heights,N.J.) at about 82° C. for about 10 minutes, and rinsing with tap waterand then deoxidized by immersing in a 71° C. bath of concentratedsulfuric acid, sodium dichromate and water for about 10 minutes (this isknown as Forest Lake Products Etch Systems or FPL Etch System) followedby rinsing with deionized water and finally anodized by immersion inphosphoric acid at 22° C. with applied voltage of 15 volts for 20-25minutes followed by rinsing with tap water (test for water break) andair drying 10 minutes at 22° C. and 10 minutes at 71° C. The total areato be bonded on both panels was primed with corrosion inhibiting primerfor aluminum (3M EC-3924B). Test bonds were assembled using a singlelayer of film, and assemblies were cured in an autoclave at a pressureof about 20.7 N/cm² for 90 minutes at about 132° C.-138° C.

Glass transition temperature was determined using a DifferentialScanning Calorimeter (DSC). Test results are presented in Table I below.

For a comparative example, an adhesive film was analogously preparedusing Bisphenol A in place of Monomer F. In particular, using ananalogous procedure to that described above, a "Film B" was preparedusing the following:

    ______________________________________                                        Ingredient                  Amount                                            ______________________________________                                        Component A:  Epon ® 829                                                                              44.3   g                                                        Bisphenol A   8.0                                                             HC-1101       12.4                                              Component B:  Epon ® 828                                                                              8.1    g                                                        Dicyandiamid  4.5                                                             TDI Urea      1.8                                                             Epon ® 828                                                                              7.2                                                             Epon ® 834                                                                              10.0                                                            Bisphenol A   8.0                                               ______________________________________                                    

Film B was tested as described above, and the results are also presentedin Table I below.

                  TABLE I                                                         ______________________________________                                                Cure Temp.                                                                              Test Temp.                                                                              Test Results                                      Property  °C.  °C.                                                                              Film A Film B                                 ______________________________________                                        Tg (C)                          127.5  109.7                                  Peel (kg/cm)                                                                            135          22       13.0   12.9                                   Overlap Shear                                                                           135          22       38.5   34.5                                   (MPa)                                                                         Overlap Shear          94       26.1   18.8                                   (MPa)                                                                         Overlap Shear         121       21.2   11.3                                   (MPa)                                                                         Overlap Shear         149       13.7   3.0                                    (MPa)                                                                         Overlap Shear         177       3.1    1.7                                    (MPa)                                                                         ______________________________________                                    

The data of Table I indicates the replacement of bisphenol A withMonomer F produces substantial increase in glass transition temperature(Tg), and hence a higher (improved) temperature performance, without adetraction from peel and shear strengths. That is, Monomer F results inhigher glass transition temperature without any high densitycross-linking. It is noted that at higher temperatures, improvement inshear strength (i.e. ductility) was observed.

EXAMPLE 3 COMPARATIVE FORMULATIONS

The following examples concern comparisons between formulations anddemonstrate increased Tg and ductility attainable using epoxycompositions of the present invention.

Six epoxy compositions were prepared using the formulations outlined inTable II below, by mixing the combined ingredients in a container andheating in an oven for 150° C. for about 30 minutes, followed by heatingat 177° C. for about 240 minutes. The six compositions are identified asA, B, C, D, E and Ex.2, The cured resins were allowed to cool at 25° C.,were cut into suitable sample sizes and were tested for fracture energy,determined by compact tension according to ASTM E-399-83. They were alsotested for glass transition temperature (Tg), as measured byDifferential Scanning Calorimeter. The results were as follows:

                                      TABLE II                                    __________________________________________________________________________                     Monomer                                                                             Bisphenol      Fracture                                Epoxy (1) Curative (2)                                                                         F (3) A (4) Wt % (5)                                                                            Tg Energy                                  Eq.       NH Eq. OH Eq.                                                                              OH Eq.                                                                              Toughener                                                                           °C.                                                                       J/m.sup.2                               __________________________________________________________________________    Ex. A.sup.6                                                                       0.5   0.5                      208                                                                               65                                     Ex. B.sup.6                                                                       0.5   0.25   0.25              185                                                                              190                                     Ex. C.sup.6                                                                       0.5   0.25         0.25        137                                                                              180                                     Ex. D.sup.6                                                                       0.5   0.5                5     204                                                                              120                                     Ex. 2'                                                                            0.5   0.25   0.25        5     l83                                                                              1600                                    Ex. E.sup.6                                                                       0.5   0.25         0.25  5     136                                                                              1850                                    __________________________________________________________________________     (1) 2,2bis[4(2,3epoxypropoxy)phenyl]propane                                   (2) diaminodiphenylsulfone                                                    (3) 9,9bis(4-hydroxyphenyl)fluorene, OH eq. wt. 175                           (4) OH eq. wt. 114                                                            (5) KM 653, Rohm and Haas Co., Philadelphia, Pa. This substance is a          core/shell copolymer of polymethacrylate rigid shell with an elastomeric      core of crosslinked styrene/butadiene.                                        (6) Described in the text as Comparative Examples A, B, C, D and E.      

Table II demonstrates several embodiments of the invention. The additionof the diphenol in B and C demonstrates that the use of chain extensionagent (Monomer F or bisphenol A) in place of a portion of the curativeused in comparative Example A will significantly increase the toughnessof the cured resin, see Comparative Examples B and C. However, whenbisphenol A is used as a chain extension agent (Comparative Example C),a drastic and undersirable reduction in the glass transition temperatureresults. When the fluorene bisphenol, Monomer F, is used the toughnessis increased as much as it EXAMPLE for bisphenol A; but a much higherglass temperature results.

The data also demonstrates the beneficial effects of the addition of arubber toughening agent to the epoxy compositions. When a tougheningagent was added to the highly cross-linked composition (ComparativeExample D), the improvement in toughness energy was minimal. However,when the toughener was added to the chain-extended compositions, theeffect on toughness was much more pronounced, see Example 2, andcomparative Example E. Again, when Monomer F was used as the chainextension agent, the glass transition temperature is much higher thanwhen bisphenol A was used.

FORMULATIONS ACCORDING TO THE ALTERNATE EMBODIMENT Example 4

This example shows an alternate chemical route to achieve a curedadhesive resin composition similar to film A of Example 2 or Example 2'above. The composition of Example 2, was shown to have an advantageousbalance of relatively high glass transition temperature and hightoughness. The alternate chemical route, generally corresponding to thesecond embodiment of the invention described in detail above, involvesutilization of a fluorene di-epoxide, in place of the bis(hydroxyphenyl)fluorene chain extension agent.

To a resin flask fitted with a mechanical stirrer and a thermometer:21.8 gm. of "Epon" 829; and 22.5 gm. diglycidyl ether of9,9-bis(4-hydroxyphenyl) fluorene, epoxide (equivalent weightapproximately 242) ("Epon RSS 1079, Shell Chemical Company) were added.The mixture was heated to about 121° C. with continuous stirring, andwas maintained at 115°-127° C. until a uniform mixture was obtained (15to 30 minutes). Then, 11.8 gms. of 2,2-bis(p-hydroxyphenyl)propane(BPA-154, Shell Chemical Company) were added and blended untildissolved. HC 1101, 11.0 grams., which had been melted at about 82° C.was added slowly to the reaction flask, with stirring. The mixture washeated at about 135°-163° C., for about 120 minutes, was dumped andcooled at 22° C. on silicone treated kraft paper, and was then dissolvedin an 80-20 mixture of methyl ethyl ketone (MEK) and toluene, by placingin a double tite tin and rolling the mixture on a roller mill.

When dissolved, the following ingredients were added to the mixture:12.0 g. "Epon" RSS 1079; 4.2 g. BPA-154; 18.8 g. diglycidyl ether ofbisphenol A, epoxide (equivalent weight approximately l74)(DER 332, DowChemical Company); 3.0 g. diglycidyl ether of 1,4-cyclohexane dimethanol(equivalent weight approximately l65)(MK 107, Willmington ChemicalCorp.); 2.0 g. carboxy-functional liquid copolymer of acrylonitrile andbutadiene (Hycar 1300 x 31, B.F. Goodrich Company); 4.5 g. dicyandiamidepreground to an average particle size of about 10 microns; 1.4 g. TDIurea pre-ground to a average particle size of about 10 microns, andtetrahydrofuran (THF), blending with mechanical stirring to form a resinsolution of about 69.5% solids content and about 3.9:1.0:3.8MEK:toluene:THF.

For testing purposes a dry film was prepared by coating the mixture on asilicone treated polyethylene coated paper backing, at a wet thicknessof about 0.25 mm., with a drying of the film for about 60 minutes toabout 90 minutes, at about 22° C. followed by treatment for about 60minutes at 66° C. in a fresh air circulating oven. The material isidentified herein as "film 5A"

The blister detection shear strength was determined according to UnitedStates Federal Specification MMM A-l32A (incorporated herein byreference) and peel strength was determined according to ASTM D-3167-7b(incorporated herein by reference) using aluminum panels described inExample 2 above. The panels were prepared as in Example 2 above, exceptthey were not subjected to the anodizing step of immersion in phosphoricacid followed by tap water rinse. The total area to be bonded on bothpanels was primed with corrosion inhibiting primer for aluminum (3MEC-3960).

Test bonds were assembled using a single layer of "film 5A" andassemblies were cured in an autoclave at a pressure of 20.7 N/cm² for 90minutes at about 132° C. to 138° C. Test results are presented in TableIII below.

                  TABLE III                                                       ______________________________________                                                    Cure Temp. Test Temp. Test Results                                Property    C.         C.         Film 5A                                     ______________________________________                                        Peel (kg/cm)                                                                              135         22        16.2                                        Blister Detection                                                                         135         22        39.4                                        Overlap Shear                                                                 (MPa)                                                                         Blister Detection      121        28.8                                        Overlap Shear                                                                 (MPa)                                                                         Blister Detection      149        18.8                                        Overlap Shear                                                                 (MPa)                                                                         ______________________________________                                    

The date of Table III indicates that the introduction offluorene-containing moieties as di-epoxide component (instead as diolchain extension agent) also produces a high (improved) temperature shearperformance, without a detraction from peel strength. Glass transitiontemperature (Tg) was not measured, but would be expected to be similaras that for film A of Example 2 above.

COMPARATIVE FORMULATIONS EXAMPLE 5

The following Examples concern comparisons between formulations with andwithout fluorene-containing component (provided by means of a fluorenedi-epoxy) and demonstrate increased hot strength obtainable without lossof toughness (as measured by peel strength of the cured adhesive).

Three toughened epoxy compositions were prepared using the formulationsoutlined in Table IV below, by first melting the epoxide components, inthe amounts stated, in a resin flask fitted with a mechanical stirrer.HC 1101, which had been melted at about 82° C. was added slowly to thereaction flask, with stirring. The mixture was heated to about 115°-135°C. for about 60 minutes, cooled to about 25° C, and then ethyl acetatewas added with stirring until a uniform mixture resulted.

Diaminodiphenylsulfone, which had been jet milled to about 5 to 10micron particle size, was added to the mixture with stirring to yield afinal coating solution of about 83-87% solids content.

For testing purposes, a dry film was prepared by coating the mixture ona silicone treated polyethylene coated paper backing at a wet thicknessof about 0.23 mm., with a drying of the film for about 60-90 minutes atabout 22° C., followed by treatment for about 60 minutes at about 60° C.under fresh air circulating oven.

The blister detection shear strength was determined as in Example 4,except that the panels for determining shear strength were primed with3M EC-3917 in place of 3M EC-3960.

Test bonds were assembled using a single layer of the film as preparedabove, cured in an autoclave at a pressure of about 13.8 N/cm² for about120 minutes at about 177° C. (1/4°-180° C.). Test results are presentedin Table V below.

                  TABLE IV                                                        ______________________________________                                                       Amount                                                         Ingredient      Ex. 4A    Ex. 4B  Ex. 4C                                      ______________________________________                                        "Epon" 828      50        50      25                                          diglycidyl ether of                                                                           50        25      25                                          bisphenol A, epoxide (1)                                                      "Epon" RSS 1079 --        25      50                                          HC 1101         14.4      15.4    15.1                                        diaminodiphenyl-                                                                              29.5      38.9    35.9                                        sulfone (2)                                                                   ______________________________________                                         (1) Equivalent weight 2250, "Epon" 1007, Shell Chemical Co.                   (2) Eporal, CibaGeigy Corporation                                        

                  TABLE V                                                         ______________________________________                                                           Test                                                                  Cure Temp                                                                             Temp    Test Results                                       Property     C.        C.      4A   4B   4C                                   ______________________________________                                        Peel (N/25 mm)                                                                             177        22     56.9 61.3 96.3                                 Blister Detection                                                                          177       149     6.2  13.2 15.0                                 Overlap Shear (MPa)                                                           Blister Detection      177     4.0  10.5 14.3                                 Overlap Shear (MPa)                                                           Blister Detection      204     1.9  3.5  7.8                                  Overlap Shear (MPa)                                                           Blister Detection      232     1.4  2.4  4.1                                  Overlap Shear (MPa)                                                           ______________________________________                                    

The data of Table V indicates that increasing amounts offluorene-containing component produces corresponding increases in shearstrength at high test temperatures and peel strength (toughness).Although glass transition temperatures were not measured, based on thehigh temperature shear performance 4C would be expected to be of highestTg, and 4A would be expected to be of lowest Tg, analogously to Example2.

FURTHER GENERAL STATEMENTS OF THE INVENTION

From the previous examples, it will be understood that generallyaccording to the present invention an improvement in the cured productof an epoxy resin is accomplished through provision of an agentcontaining a selected fluorene residue IV as an extension agent in theepoxy resin composition to be cured or cross-linked. The agent may beprovided as a diol chain extension agent or as a chain extendingdiepoxide. Specifically, improvement is obtained through the utilizationof a 9,9-bis(hydroxyphenyl)fluorene compound, or of di-epoxidederivative, thereof (such as a diglycidyl ether, epoxide), or ofmixtures of these materials as the extension agent. The improvementsgenerally relate to: improvement in glass transition temperature (i.e.raising of glass transition temperature) without substantial loss oftoughness or ductility; or improvement in Tg without any substantialloss of toughness; or, improvement in toughness and/or ductility withoutloss of high Tg. In some instances both Tg and toughness can beimproved.

Significantly, the present invention also involves improvement, throughprovision, in addition to the extension agent, of a toughening agent inthe resin composition. As illustrated in the Examples, a significantoverall improvement is achieved when both the 9,9-fluorene residue andthe toughening agent are present.

In addition to a method of improving the epoxy resin compositions, orthe physical characteristics of cured epoxy resin compositions, thepresent invention also concerns a particular, preferred, epoxy resincomposition according to the above general features.

It is to be understood that while certain embodiments of the presentinvention have been illustrated and described, the invention is not tobe limited to the specific forms, compositions, systems or proceduresherein described and/or illustrated.

What is claimed and desired to be secured by Letters Patent is asfollows:
 1. An adhesive bonding film/substrate arrangementcomprising:(a) a first substrate; (b) a second substrate; (c) a bondingfilm between said first and second substrates; said bonding filmcomprising a cured epoxy resin composition including:(i) between 2% and90% by weight residue units according to the formula: ##STR10## wherein:each R⁰ is independently selected from hydrogen and other groupssubstantially inert to polymerization of epoxide group-containingcompounds; and, each R¹ is hydrogen; and, (ii) an effective amount of atoughening agent.
 2. The film/substrate arrangement according to claim 1wherein said bonding film was between about 0.001 and 0.070 cm thick,prior to cure.
 3. A film/substrate arrangement according to claim 1wherein:(a) each R⁰ is independently selected from the group consistingof: hydrogen; the halogens; alkyl groups having 1-6 carbon atoms;phenyl; nitro; acetyl; and, trimethylsilyl.
 4. A film/substratearrangement according to claim 3 wherein each R⁰ is hydrogen.
 5. Afilm/substrate arrangement according to claim 1 wherein said cured epoxyresin composition includes between about 2% and 78% by weight of saidresidue units.
 6. A film/substrate arrangement according to claim 1wherein said cured epoxy resin composition includes between about 4% and60% by weight of said residue units.
 7. A film/substrate arrangementaccording to claim 1, wherein said toughening agent is selected from thegroup consisting of: acrylic core/shell polymers;styrene-butadiene/methacrylate core/shell polymers; polyether polymers;carboxylated acrylonitrile/butadienes; and, carboxylated butadienes. 8.An adhesive bonding film/substrate arrangement comprising:(a) a firstsubstrate; (b) a second substrate; and, (c) a bonding film between saidfirst and second substrates; said bonding film comprising a cured epoxyresin composition formed from a precursor composition including:(i) afluorence di-epoxide composition in an amount of between 0.05 and 0.9epoxy equivalents of said di-epoxide composition per group reactive withsaid fluorene di-epoxide composition; said fluorene di-epoxidecomposition being of the general formula: ##STR11## wherein: each R^(o)is independently selected from hydrogen and other groups substantiallyinert to polymerization of epoxide group-containing compounds; each R¹is hydrogen; and, each R² is an epoxy-functionalized alkyl group capableof reacting through the epoxy group to form an epoxy resin; and, (ii) aneffective amount of a toughening agent.
 9. A film/substrate arrangementaccording to claim 8 wherein:(a) each R⁰ is independently selected fromthe group consisting of: hydrogen; the halogens; alkyl groups having 1-6carbon atoms; phenyl; nitro; acetyl; and, trimethylsilyl.
 10. Afilm/substrate according to claim 8 wherein each R⁰ is hydrogen and eachR² is a 2,3-epoxypropyl group.
 11. A film/substrate arrangementaccording to claim 8 wherein said bonding film was between about 0.001and 0.070 cm thick, prior to cure.
 12. A film/substrate arrangementaccording to claim 9 wherein each R² is a terminal epoxy-functionalizedalkyl group having 1-6 carbon atoms.
 13. A film/substrate arrangementaccording to claim 8 wherein said precursor composition includes betweenabout 0.09 and 0.7 epoxy equivalents of said fluorene di-epoxidecomposition per group reactive with said fluorene di-epoxidecomposition.
 14. A film/substrate arrangement according to claim 8wherein said toughening agent is selected from the group consisting of:acrylic core/shell polymers; styrene-butadiene/methacrylate core/shellpolymers; polyether polymers; carboxylated acrylonitrile/butadienes;and, carboxylated butadienes.
 15. A method of adhering substratescomprising the steps of:(a) providing first and second substrates; (b)providing an adhesive epoxy resin composition between said first andsecond substrates; and, (c) curing said adhesive epoxy resin compositionto form a cured adhesive bonding film including:(i) between 2% and 90%by wight residue units of the general formula: ##STR12## wherein: eachR⁰ is independently selected from hydrogen and other groupssubstantially inert to polymerization of epoxide group-containingcompounds; and, each R¹ is hydrogen; and, (ii) an effective amount of atoughening agent.
 16. A method of adhering substrates according to claim15 wherein:(a) each R⁰ is independently selected from the groupconsisting of: hydrogen; the halogens; alkyl groups having 1-6 carbonatoms; phenyl; nitro; acetyl; and, trimethylsilyl.
 17. A methodaccording to claim 16 wherein: each R⁰ is hydrogen.
 18. A method ofadhering substrates according to claim 15 wherein said step of providingan adhesive epoxy resin composition includes providing said compositionin a film of between about 0.001 and 0.070 cm thick.
 19. A method ofadhering substrates according to claim 15 wherein said cured adhesivebonding film of said epoxy resin composition includes between about 2%and 78% by weight of said residue units.
 20. A method of adheringsubstrates according to claim 15 wherein said cured adhesive bondingfilm of said epoxy resin composition includes between about 4% and 60%by weight of said residue units.
 21. A method of adhering substratescomprising:(a) providing first and second substrates; (b) providing anadhesive epoxy resin composition between said first and secondsubstrates, wherein said resin composition includes:(i) a fluorenedi-epoxide composition in an amount of between 0.05 and 0.9 epoxyequivalents of said di-epoxide per group reactive with said fluorenedi-epoxide composition; said fluorene di-epoxide composition being ofthe general formula: ##STR13## wherein: each R⁰ is independentlyselected from hydrogen and other groups substantially inert topolymerization of epoxide group-containing compounds; each R¹ ishydrogen; and, each R² is an epoxy-functionalized alkyl group capable ofreacting through the epoxy group to form an epoxy resin; and, (ii) aneffective amount of a toughening agent; and, (c) curing said adhesiveepoxy resin composition to form a cured adhesive bonding film.
 22. Amethod of adhering substrates according to claim 21 wherein:(a) each R⁰is independently selected from the group consisting of: hydrogen; thehalogens; alkyl groups having 1-6 carbon atoms; phenyl; nitro; acetyl;and, trimethysilyl; and, (b) each R² is a terminal epoxy-functionalizedalkyl group having 1-6 carbon atoms.
 23. A method according to claim 21wherein each R⁰ is hydrogen and each R² is a 2,3-epoxypropyl group. 24.A method of adhering substrates according to claim 27 wherein:(a) eachR⁰ is independently selected from the group consisting of: hydrogen; thehalogens; alkyl groups having 1-6 carbon atoms; phenyl; nitro; acetyl;and, trimethylsilyl; and, (b) each R² is a terminal epoxy-functionalizedalkyl group having 1-6 carbon atoms.
 25. A method of adhering substratesaccording to claim 27 wherein each R⁰ is hydrogen and each R² is a2,3-epoxypropyl group.
 26. A method of adhering substrates according toclaim 21 wherein said step of providing an adhesive epoxy resincomposition includes providing said composition in a film of betweenabout 0.0001 and 0.070 cm thick.
 27. A method of adhering substratesaccording to claim 21 wherein said resin composition includes betweenabout 0.05 and 0.9 molecules of a diol chain extender per reactive epoxymolecule.
 28. An adhesive resin composition comprising:(a) a polyepoxideresin; (b) between about 5% and 97% by weight of a fluorene di-epoxidecomposition of the general formula: ##STR14## wherein: (i) each R⁰ isindependently selected from the group consisting of: hydrogen; thehalogens; alkyl groups having 1-6 carbon atoms; phenyl; nitro; acetyl;and, trimethylsilyl;(ii) each R¹ is hydrogen; and (iii) each R² is aterminal epoxy-functionalized alkyl group having 1-6 carbon atoms; (c)between about 0.05 and 0.9 epoxy equivalents of said fluorene di-epoxidecomposition per group reactive with said fluorene di-epoxidecomposition; (d) between about 0.05 and 0.9 molecules of a diol chainextender per reactive epoxy molecule; and, (e) an effective amount of atoughening agent.
 29. An adhesive resin composition according to claim28 wherein each R⁰ is hydrogen and each R² is a 2,3-epoxypropyl group.30. An adhesive resin composition according to claim 28 comprisingbetween about 0.09 and 0.7 epoxy equivalents of said fluorene di-epoxidecomposition per group reactive with said fluorene di-epoxidecomposition.
 31. An adhesive resin composition according to claim 28comprising between about 0.09 and 0.7 molecules of a diol chain extenderper reactive epoxy molecule.
 32. An adhesive resin composition accordingto claim 28 further comprising an effective amount of a curative.
 33. Anadhesive resin composition according to claim 28 wherein said tougheningagent is selected from the group consisting of: acrylic core/shellpolymers; polyether polymers; carboxylated acrylonitrile/butadienes;and, carboxylated butadienes.
 34. An adhesive resin compositionaccording to claim 29 comprising between about 0.09 and 0.7 epoxyequivalents of said fluorene di-epoxide composition per group reactivewith said fluorene di-epoxide composition.
 35. An adhesive resincomposition according to claim 29 further comprising an effective amountof a curative.
 36. An adhesive resin composition according to claim 35wherein said curative contains at least 3 reactive sites.
 37. Anadhesive resin composition comprising:(a) a polyepoxide resin; (b)between about 5% and 97% by weight of a fluorene di-epoxide compositionof the general formula: ##STR15## wherein: (i) each R⁰ is independentlyselected from the group consisting of: hydrogen; the halogens; alkylgroups having 1-6 carbon atoms; phenyl; nitro; acetyl; and,trimethlysilyl;(ii) each R¹ is hydrogen; and, (iii) each R² is anepoxy-functionalized alkyl group capable of reacting through the epoxygroup to form an epoxy resin; (c) between about 0.05 and 0.9 epoxyequivalents of said fluorene di-epoxide composition per group reactivewith said fluorene di-epoxide composition; and, (d) an effective amountof a toughening agent.
 38. An adhesive resin composition comprising:(a)a polyepoxide resin; (b) a fluorene di-epoxide composition in an amountof between 0.05 and 0.9 epoxy equivalents per group reactive with saidfluorene di-epoxide; said fluorene di-epoxide composition being of thegeneral formula: ##STR16## wherein: (i) each R⁰ is independentlyselected from the group consisting of: hydrogen; the halogens; alkylgroups having 1-6 carbon atoms; phenyl; nitro; acetyl; and,trimethylsilyl;(ii) each R¹ is hydrogen; and (iii) each R² is a terminalepoxy-functionalized alkyl group having 1-6 carbon atoms; and, (c)between about 0.05 and 0.9 molecules of a diol chain extender perreactive epoxy molecule.
 39. An adhesive resin composition according toclaim 38 wherein each R⁰ is hydrogen and each R² is a 2,3-epoxypropylgroup.
 40. An adhesive resin composition according to claim 38comprising between about 0.09 and 0.7 epoxy equivalents of said fluorenedi-epoxide composition per group reactive with said fluorene di-epoxidecomposition.
 41. An adhesive resin composition according to claim 38comprising between about 0.09 and 0.7 molecules of a diol chain extenderper reactive epoxy molecule.
 42. An adhesive bonding film/substratearrangement comprising:(a) a first substrate; (b) a second substrate;and, (c) a bonding film between said first and second substrates; saidbonding film comprising a cured epoxy resin composition including:(i)between 2 and 90% by weight residue units according to the formula:##STR17## wherein: each R⁰ and R¹ is independently selected fromhydrogen and other groups substantially inert to polymerization ofepoxide group-containing compounds; and, (ii) an effective amount of atoughening agent.
 43. An adhesive resin composition comprising:(a) apolyepoxide resin; (b) between about 5% and 97% by weight of a fluorenediepoxide composition of the general formula: ##STR18## wherein: (i)each R⁰ is independently selected from the group consisting of:hydrogen; the halogens; alkyl groups having 1-6 carbon atoms; phenyl;nitro; acetyl; and, trimethylsilyl;(ii) each R¹ is independentlyselected from the group consisting of: hydrogen; phenyl; the halogens;and, alkyl groups having 1-6 carbon atoms; and, (iii) each R² is anepoxy-functionalized alkyl group capable of reacting through the epoxygroup to form an epoxy resin; (c) between about 0.05 and 0.9 epoxyequivalents of said fluorene di-epoxide composition per group reactivewith said fluorene di-epoxide composition; and, (d) an effective amountof a toughening agent.
 44. A method of adhering substrate comprising:(a)providing first and second substrates; (b) providing an adhesive epoxyresin composition between said first and second substrates; and, (c)curing said adhesive epoxy resin composition to form a cured adhesivebonding film including:(i) between 2% and 90% by weight residue units ofthe general formula: ##STR19## wherein: each R⁰ and R¹ is independentlyselected from hydrogen and other groups substantially inert topolymerization of epoxide group-containing compounds; and, (ii) aneffective amount of a toughening agent.
 45. A method of adheringsubstrates according to claim 2 wherein said resin composition furtherincludes an effective amount of a curative.
 46. An adhesive resincomposition comprising:(a) a polyepoxide resin; (b) between about 5% and97% by weight of a fluorene diepoxide composition of the generalformula: ##STR20## wherein: (i) each R⁰ is independently selected fromthe group consisting of: hydrogen; the halogens; alkyl groups having 1-6carbon atoms; phenyl; nitro; acetyl; and, trimethylsilyl;(ii) each R¹ isindependently selected from the group consisting of: hydrogen; phenyl;the halogens; and, alkyl groups having 1-6 carbon atoms; and, (iii) eachR² is a terminal epoxy-functionalized alkyl group having 1-6 carbonatoms; (c) between about 0.05 and 0.9 epoxy equivalents of said fluorenedi-epoxide composition per group reactive with said fluorene di-epoxidecomposition; (d) between about 0.05 and 0.9 molecules of a diol chainextender per reactive epoxy molecule; and, (e) an effective amount of atoughening agent.